Fluid dynamic bearings have come into increasingly widespread use, especially in fields where the stability of the shaft and bearing assembly is of critical importance, such as in the field of disk drives and the like. Ball bearing assemblies have many mechanical problems such as wear, run-out and manufacturing difficulties. Moreover, resistance to operating shock and vibration is poor because of flow damping. Thus, fluid dynamic bearings where in a lubricating fluid such as gas or liquid or air provides a bearing surface between a fixed member of the housing and a relatively rotating member have come into increasingly wide-spread use. Such fluid dynamic bearings spread the bearing surface over a large continuous area in comparison with the ball bearing assembly which comprises a series of point interfaces. This is desirable because the increased bearing surfaces reduce wobble or run-out between the rotating and fixed members. Further, improved shock resistance and readiness is achieved with a fluid dynamic bearing. Also, the use of fluid in the interface area imparts damping effects to the bearing.
An especially desirable design is a conical bearing, as a single bearing or a pair of facing bearings can impart substantial radial and axial stability to a system.
However, due to nominal gaps in a conical fluid bearing on the order of 1 to 3 microns, precise size and positional control must be maintained during component fabrication and assembly. If not done, the assembled components will not have the proper geometric relationships necessary to produce a functional air bearing when the parts rotate at the operating speed.